Recent studies by ExxonMobil, Shell and Unocal have shown the benefits of synthetic base drilling fluids (SDF's) in the evolution of environmentally friendly replacements for petroleum derived analogs. Essentially all commercial current day drilling fluid formulations are based on refinery extraction, severe hydrotreatment, by partly polymerizing linear olefins to produce low molecular weight linear alpha olefins, or by other olefin oligomerization and/or condensation reactions, Fischer-Tropsch synthesis, and various transesterification reactions of natural fatty acids with alcohol streams. Important characteristics of SDFs include their viscometric and volatility characteristics, toxicity and biodegradability. Current SDFs are discussed in a recent report by Shell appearing at: http://www.shell.com/home/content/chemicals/products_services/our_products/alpha_olefins_detergent_alcohols/neoflo/synthetic_drilling_fluids_defined/neoflo_synthetic_fluids.html.
The term “synthetic” as it applies to fluids herein, generally refers to materials that are not normally found in nature, and that are manufactured by chemical processes, as opposed to being extracted from refinery streams, which extracted streams are generally referred to as being “petroleum-based.” Typical SDF's have been internal olefins, alpha olefins, polyalphaolefins, paraffins, esters and blends of these materials. These fluids offer improved lubricity, thermal stability, and well-bore integrity. Formulated synthetic drilling fluids are typically made up of about 60 to 80% of an SDF, about 10 to 15% of emulsifier and surfactant components, and inorganic fillers such as alumina or silica.
The environmental properties of base fluids depend on the physical and chemical characteristics of the material. Olefin and paraffin base fluids and diesel will biodegrade aerobically. However, under anaerobic conditions, alpha olefin and internal olefin base fluids biodegrade more extensively (>50%) than paraffins and diesel (<5-20%). As a result, paraffin base fluids may persist in the environment for longer periods of time if they are not exposed to aerobic conditions. Ideally, base drilling fluids should be biodegradable under both aerobic and anaerobic conditions.
Important characteristics of aviation fuel blend stocks, especially for jet fuels, include theft low temperature properties, oxidative and thermal stability, energy content, and system compatibility, including effects on metal corrosion and integrity of seals and gaskets, toxicity and biodegradability. With today's increasing environmental concerns, the greenhouse gas lifecycle analysis (LCA) has become an important characteristic of aviation fuels. It is extremely difficult or impossible to obtain a favorable balance of all of these characteristics with current petroleum derived aviation fuels. For example, such aviation fuel blend stocks or typically contain significant amounts of poly-nuclear aromatics and complex polyunsaturates that are toxic to humans and animals.
International patent application publication number WO 2009/025663 A1 describes processes for producing jet fuel blend stocks from biologically produced triglyceride fatty acids (TGFA's) obtained from medium chain length TGFA's, such as cuphea, in which the fatty acid groups have no more than 16 carbon atoms, by cleaving the medium chain fatty acid groups from the glycerides and decarboxylating and isomerizing the fatty acids to form hydrocarbons for the production of jet fuel. The disclosed method attempts to mimic the molecular weight distribution of typical jet fuels, such as JP 8, by blending oils from various biologic TGFA's. It is difficult or impossible, however, to precisely control the degree of cracking and isomerization of the various carbon chain length molecules in the fatty acids, thereby compromising the properties of the produced or jet fuel blend stock. The disclosure of WO 2009/025663 A1 is hereby incorporated by reference in its entirety for all purposes.